Arrangement for protecting vacuum tubes

ABSTRACT

189,095. Ges. f³r Drahtlose Telegraphie. Nov. 14, 1921, [Convention date]. Vacuum tubes.-In a valve generator overheating of the anode is prevented by the provision of an auxiliary anode, by means of which the feed current circuit is interrupted or reduced when the temperature of the anode rises. The auxiliary anode 4 is connected through a battery 5 and a relay 6 with the anode 3, which, when overheated, emits electrons, which pass to the auxiliary anode 4, and the resulting current causes the relay to open the contacts 9 of the feed circuit 7, 8. The battery 5 may be replaced by a supply of rectified current.

-A. MEISSNER ARRANGEMENT FOR PROTECTING VACUUM TUBES June 17, 1930. 1,763,805

Filed Nov. 14, 1922 MAIN SOURCE OF ENERGY.

ill! awmz/wccvc ALEXANDER MHSSNER Patented June 17; 1930 UNITED STATES PATENT OFFICE ALEXANDER MEISSNER, OF BERLIN, GERMANY, AS SIGNOR TO GESELLSCHAF'I. F'UR DRAHTIOSE TELEGRAPHIE M. B. H. HALLESCHES, OF BERLIN, GERMANY, A COR- PORATION OF GERMANY ARRANGEMENT FOR PROTECTING VACUUM TUBES Application filed November 14, 1922, Serial 110. 600,846, and in Germany November 14, 1921.

F or the economical operation of large transmitting tubes, it is. necessary that they be adjusted to a favorable operating range and that the individual tubes be so proportioned that this operating range is constantly maintained. It is necessary for this purpose to prevent the rising of the anode current to a point where it over-heats the anode plates. Usually the anode plates show scarcely any signs of glowing or are brought juitt to a red glow because otherwise the gener or tubes would be endangered.

The object of the present invention is to prevent the over-loading of tubes, particularly transmitting tubes. This is accomplished by providing a current path between the anode of a tube and a special auxiliary electrode. A relay may be inserted in the circuit which includes this path, the relay being actuated when, upon the over-heating of the anode, a heavy stream of electrons flows from the anode plate to the auxiliary electrode and thereby causes a current to be generated that'energizes the relay. The relay may then cause cutting in of the necessary resistance, disconnection of the individual circuits or the like to prevent over-loading of the tube. V The single figure of the drawing is a diagrammatic representation of a circuit arrangementembodying the present invention.

In said figure the generator tube 2 which is coupled with the-antenna 1 includes near its anode 3 an auxiliary anode 4 which is connected with a relay 6 through a battery 5. The otlier end of the relay 6 is connected with the anode 3, and the armature 7 of the relay is grounded through a wire 8. The

battery 5 is not absolutely necessary, but on the contrary, any other suitable current source may be provided in its stead, e. g. the alternating current used for feeding the cathode generator may be used after rectification. The main battery or-rectifier is connected to the binding posts 9 and 10.

The operation is as follows:

When the main anode 3 carries the normal load so that it does not glow, no current, flows through the relay 6. If however, due to any operation, e. g. detum'ng of the antenna 1 with respect, to the oscillating circuit, the anode coupling is disturbed or the operating condition is otherwise unbalanced, resulting in glowing of the anode 3, electrons Will be emitted by this anodeland absorbed. by the auxiliary anode 4. The anode 3 udder such conditions .operates as a cathode in the relay circuit. Therefore, current flows through the relay 6 which is closely dependent on the temperature of the anode. As a result of this the contacts 11 of the relay are separated, whereupon the main anode current is interrupted and the over-loading and destruction of the tube 2 prevented.

Obviously, the invention is subject to modifipations of widely varying character. For instance, .it is not necessary that the main current be entirely interrupted, it being sufficient that under the control of the auxiliary anode 4, the heating or the anode potential is directly or indirectly affected.

Having described my invention, what I claim'is: I

-1. A circuit arrangement comprising a three-electrode vacuum tube, an anode, a

electrode mounted in the tube, a normally inoperative circuit including said last-named electrode and said anode and through which current may be set up'upon overheating of the anode and means in said last-mentioned circuit for limiting the current in the main anode circuit to prevent over-heating of the anode.

3. In combination, a thermionic tube havingan' anode and cathode, means whereby a current may flow through said anode and cathode, and means dependent upon the electron-emittin property of said anode for li-miting the sai current.

4. In combination, a thermionic tube hav ing an anode and a cathode, means whereby 5 current may flow through said anode and cathode. and means including an auxiliary electrode adapted to control said current when said anode is overheated.

5. In combination, a thermionic tube having an anode, a grid and a cathode, means for impressing a variable potential on said grid, means whereby current may flow through said anode and cathode, an auxiliar electrode, a circuit connecting said ano e and auxiliary electrode, and current limiting means associated with said circuit for controlling said current and adapted to be actuated by current flowing in said circuit.

6. In combination, a thermionic tube hav- 2o ing three associated electrodes, an anode circuit having a source of anode potential and a pair of relatively movable contacts, a fourth electrode, an auxiliary circuit including said anode, said fourth electrode, a source of current, and an electro-magnetic means for controlling said contacts, said latter means' being actuated by a flow of current in said auxiliary circuit.

7. In combination, an electron discharge 3o device comprising an anode and cathode, a gircuit for maintaining a potential difiernce between the ano e and cathode and means dependent on the electron emitting property of said anode for interrupting said 3'5 circuit.-

8. In an electric discharge device, a circuit including a cathode and an electrode normally an anode, a second circuit including said electrode and a relay, said electrode upon a 40 reaching a predetermined temperature oper- Qting as a cathode in the second circuit to ause operation of the rela ALEXANDE MEISSNER 

